Wild elephants sleep just two hours a night

ELEPHaNTS survive on just two hours of sleep a night, a wildlife study shows.

They often go without rest for as long as 46 hours while covering distances of almost 20 miles. Most studies on their sleep had been done in a captive setting only.

But for the latest study researchers monitored two free-roaming african elephant matriarchs in Chobe National Park, Botswana, for 35 days.

They fitted the elephants with an electronic monitoring device implanted in the trunk to track sleep accurately. They also used a collar with a gyroscope to track sleeping position.

They found that the elephants slept an average of two hours a day, which is the shortest known time of any land mammal.

On several days during the study, the elephants went without sleep for up to 46 hours and travelled long distances of around 19 miles, possibly due to disturbances such as lions or poachers. The ele- phants slept lying down only every few nights, the tracking devices showed.

The researchers said this could limit their potential for daily rapid eye movement sleep, raising questions about how frequently elephants experience the kind of sleep required for dreaming.

While only two elephants were tracked, the researchers say their findings provide insights into the sleep patterns of elephants in the wild.

Paul Manger, who led the study at the University of the Witwatersrand in South africa, said: ‘Studies of sleep in captive ele- phants have shown that they sleep for four to six hours per day.

‘However, the current study shows that in their natural habitat, wild, free-ranging elephants sleep only for two hours per day, the least amount of sleep of any mammal studied to date, but this appears to be related to their large body size.’

Professor Manger added: ‘In addition, it appears that elephants only go into REM, or dreaming, sleep every three to four days, which makes elephant sleep unique.’

The findings were published in the scientific journal PLOS ONE.